Disputas - Master of Science Nikhil Jayakumar

Master of Science Nikhil Jayakumar will Tuesday February 6th, 2024, at 12:15 hold his disputas for the PhD degree in Science. The title of his thesis is:

"Label-free super-resolution optical microscopy"

Summary:

To see structures well below 200 nm using visible light, super-resolution techniques have been developed. Most of these techniques rely on fluorescence labelling or use of artificial materials to go beyond the Abbe limit. Therefore, achieving super-resolution in the label-free regime is the problem that is being addressed in this thesis. In this work, high-index contrast dielectric waveguides are employed for microscopy. Typically, wide waveguides are employed for bio-imaging applications. High-index contrast wide waveguides support multiple optical modes to guide optical power along its length. Therefore, the first task was to use multiple modes to artificially induce intensity fluctuations that are compatible with fluorescence based super-resolution algorithms. This enabled the generation of super-resolved fluorescence images. The next task was to see if these multiple-modes can be used to illuminate unlabeled samples. By averaging several images within the integration time of the camera, a high-contrast label-free image was generated using these waveguides. Finally, to achieve super-resolution in label-free mode, photoluminescence in Si3N4 waveguides was used for near-field illumination of unlabeled samples. This helped realize a label-free incoherent imaging system, thus permitting the application of fluorescence-based super-resolution algorithms to achieve super-resolution in label-free mode.

Evaluation committee:

• Professor Fredrik Höök, Chalmers University of Technology, Göteborg, Sweden (1. Opponent)
• Professor YongKeun (Paul) Park, Endowed Chair Professor of Physics at KAIST, South Korea (2. Opponent)
• Associate Professor Jana Jágerská, Department of Physics and Technology, UiT (intern member and leader of the committee)

The disputas will be led by Professor Unni Pia Løvhaug, Department of Physics and Technology, UiT.

Supervisors:

• Professor Balpreet Singh Ahluwalia, Department of Physics and Technology, UiT (main supervisor)
• Researcher Azeem Ahmad, Department of Physics and Technology, UiT
• Professor Olav Gaute Hellesø, Department of Physics and Technology, UiT

Streaming site:

Thesis